There exist a number of methods for growing epitaxial films on substrates. Chemical vapor deposition and molecular beam epitaxy are commonly used for growing single crystal silicon and other group III-V compound semiconductor films on single crystal substrates. The chemical vapor deposition processes typically take place at a relatively high temperature of 700 to 1000 degrees centigrade, partially to provide a small amount of mobility to the material being deposited in an attempt to grow single crystal films on a single crystal lattice. Such high temperature processes, however, may introduce strain to the epitaxial fihn on cooling due to mismatch in thermal expansion between the substrate and the film. Also, such chemical vapor deposition methods typically utilize expensive and extremely toxic feed gases to effect the process.
There is currently much effort being made to deposit single crystal diamond on non-diamond substrates. For example, it would be desirable to grow diamond on silicon so that existing microcircuit technology can be used to form circuits in the diamond film. However, single crystal diamond has successfully been grown only on natural diamond substrates using chemical vapor deposition. It has recently been reported that a group from North Carolina State University has fabricated continuous diamond films on single crystal copper substrates. The reported process involves implanting carbon into copper and heating the implanted surface with a high energy extremely short laser pulse to melt only the upper portion of the substrate including the implanted carbon. The carbon then solidifies as single crystal diamond. However, the single crystal copper substrate material is extremely expensive. In addition, the size of the film is inherently limited by the small area of the laser beam used to melt the copper (up to 1 cm2). Further, the method reportedly results in a diamond fihn of only 500 Angstroms thickness, which would be useful only as a seed for growing thicker films through conventional chemical vapor deposition techniques.